This invention relates to a non-return drainage valve provided with a self-cleaning plug and port assembly adapted for use in the floor portion of a burial casket or other container which is located in an environment wherein fluids external to the container intermittently rise from below the container to above the floor of the container. The valve allows the drainage of fluid from the container and prevents the backflow of liquid through the valve into the container due to a liquid level rising above the drainage valve located in the floor of the container.
In various containers, particularly in burial caskets, it is desirable to utilize drainage valves to allow the drainage of fluid, gases or liquids, from the container, and to prevent the flow of liquids thereinto due to liquids rising above the floor of the container in which the drainage valve is located.
One example of such a valve is disclosed in Blanchard U.S. Pat. No. 3,542,059.
In many such containers, debris from the container or from fluid contained within the container tends to pass with the flow of fluids through the drainage valve. In many instances the debris is of such size and composition so as to be unable to pass through the drain port in the drainage valve. In these cases, the debris tends to block the drain port and restrict or completely block the flow of fluids from the container through the valve. Likewise, non-liquid material may be disposed on the exterior of the container. This material may block the discharge passage of the drainage valve and prevent the drainage of fluid, gases or liquids, from the container.
This is particularly true in burial caskets and the like in which a casket has a decomposing corpse therein which produces fluids, liquids, and gases which should be drained from the burial casket. Since the burial caskets are normally placed underground, there is a problem of water entering the burial caskets through the drainage valve when the water table in the ground rises above the drainage valve in the floor of the burial casket. Further, debris from the ground can be carried with the rising water into or against the valve discharge passage thereby blocking the passage.
When the level of the water table in the ground is below the drainage valve in the burial casket, then the drainage valve opens to permit the drainage of the fluids from the interior of the burial casket. However, when this occurs, it is sometimes possible for debris from the interior of the burial vault and parts of the decomposing corpse to block the drain port in the drainage valve.